1. Field of the Invention
The present invention relates to a color liquid crystal display device, such as a color liquid crystal panel, and a manufacturing method of the same, and more particularly to a color liquid crystal display device including a color active matrix substrate composed of a substrate on which provided are thin film transistors (hereinafter, referred to as TFTs), color filters, and pixel electrodes, and a manufacturing method of the same.
2. Description of the Related Art
Today's active matrix type color liquid crystal display device employs a COT (color filter on transistor array) substrate, on which respective BGR (Blue, Green, and Red) color filters are formed as a unitary body, as an active matrix substrate provided with a matrix of pixel electrodes and a matrix of TFTs for controlling a voltage applied to the respective pixel electrodes. Liquid crystal is sandwiched between the COT substrate and a counter substrate provided to face the COT substrate, and driven by a voltage applied across the pixel electrodes and counter substrate, whereby color display is realized with color light having passed through the color filters.
FIG. 1 is a cross sectional view showing an example arrangement of a conventional COT substrate, and shows an arrangement of a COT substrate disclosed in Japanese Patent Laid-Open Publication No. Hei. 4-253028. FIG. 2 is a flowchart showing a manufacturing method of the conventional COT substrate. The following description will describe the arrangement of the conventional COT substrate with reference to FIGS. 1 and 2. Initially, as shown in Step S401 in FIG. 2, a film of tantalum (Ta) as a gate material is formed on the surface of a transparent glass substrate 401, and the film of tantalum is made into a predetermined pattern in a first photolithography process (hereinafter, referred to as PR process), whereby a gate electrode 402 and a gate bus line (not shown) are formed. Then, as shown in Step S402, after a gate insulating film 403 made of SiNx is formed, an intrinsic a-Si film (amorphous silicon film) 404 and a channel protecting film 405 are formed, and the channel protecting film 405 is made into a predetermined pattern in a second PR process. Then, as shown in Step S403, an n+ type a-Si film 406 is formed, and both the n+ type a-Si film 406 and intrinsic a-Si film 404 are patterned in a third PR process, whereby an island 407 is formed. Then, as shown in Step S404, a film of titanium (Ti) 408 is formed, which is made into a predetermined pattern in a fourth PR process, whereby a drain electrode 409, a source electrode 410, and a drain bus line (not shown) are formed.
Subsequently, as shown in Step S405, a transparent resin film 411 is formed over the entire surface, and a mask (not shown) is made into a predetermined pattern in a fifth PR process, after which an R color filter 412 is formed by selectively coloring the transparent resin film 411 in red by using the mask. Likewise, as shown in Step S406, a G color filter (not shown) is formed by selectively coloring another region of the transparent resin film 411 in green by using the mask (not shown) in a sixth PR process. Also, as shown in Step S407, a B color filter 413 is formed by selectively coloring still another region of the transparent resin film 411 in blue by using the mask (not shown) in a seventh PR process. Then, as shown in Step S408, a contact hole 414 is made through the transparent resin film 411 in an eighth PR process, so that the source electrode 410 is exposed partially. Then, as shown in Step S409, an ITO (Indium Tin Oxide) film is formed as a transparent electrode film over the entire surface, which is made into a predetermined pattern to cover regions over the respective color filters 412, 413, . . . , in a ninth PR process, whereby a pixel electrode 415 electrically connected to the source electrode 410 through the contact hole 414 is formed. Further, as shown in Step S410, the transparent resin film 411 at a region covering the island 407 is selectively colored in black by using the pixel electrode 415, whereby a BM (Black Matrix) 416 is formed. Subsequently, although it is not shown in the drawing, an orientation film is formed over the entire surface, whereupon the COT substrate is completed.
As has been discussed, with the conventional COT substrate, the gate electrode 402, channel protecting film 405 above the gate electrode 402, island 407, and drain and source electrodes 409 and 410 are formed in the TFT forming step, which requires four PR processes in total from the first through fourth PR processes. Also, the step of forming the respective RGB color filters 412, 413, . . . , and pixel electrode 415 requires five PR processes in total from the fifth through ninth PR processes. Hence, the overall fabrication step to manufacture the COT substrate requires nine PR processes in total, which involves too many manufacturing steps, thereby causing a cost increase of an active matrix type color liquid crystal display device.